Magnetism in semiconducting molybdenum dichalcogenides

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• Transition metal dichalcogenides (TMDs) are crucial 2D materials for fundamental physics and emerging technologies like spintronics.
• Understanding magnetism in semiconducting TMDs is key to unlocking novel electronic functionalities.

Purpose of the Study:

• To investigate the presence and nature of magnetic order in bulk semiconducting TMDs, specifically 2H-MoTe2 and 2H-MoSe2.
• To identify the mechanisms promoting magnetism and the types of defects involved in these materials.
• To explore the influence of external factors, such as hydrostatic pressure, on the observed magnetic properties.

Main Methods:

• Muon spin rotation (μSR) to detect magnetic order and internal magnetic fields.
• Scanning tunneling microscopy (STM) to characterize crystal defects at the atomic level.
• Density functional theory (DFT) calculations to understand defect-induced magnetism and magnetic moments.

Main Results:

• Discovery of long-range magnetic order below 40 K in 2H-MoTe2 and 100 K in 2H-MoSe2.
• Identification of metal vacancies and chalcogen-metal antisites as the primary defects promoting magnetism.
• DFT calculations confirmed magnetic moments for antisite defects (0.9–2.8 μB).
• Observed high sensitivity of magnetic order to hydrostatic pressure in both materials.

Conclusions:

• 2H-MoTe2 and 2H-MoSe2 represent a new class of magnetic semiconductors.
• Defect engineering in TMDs is a viable strategy for achieving controllable magnetism.
• These findings pave the way for exploring the interplay of 2D physics and magnetism in novel semiconductor systems.